Musical instrument



y 9, 1933- A. N. CURTISS 1,907,936

MUSICAL INSTRUMENT Filed June 9, 1952 INVENTOR Arthur- N. CLLPtLSS, B I I ATTORNEY through a Patented May 9, 1933 4 UNITED STATES PATENT OFFICE ARTHUR H. OUB'I'ISS 0F OOILINGSWOOD, NEW JERSEY, ASSIGNOR TO RADIO CORPO- BATION OF AIERICA, A CORPORATION OF DELAWARE IUSICAL INSTRUMENT Application fled June 9, 1932. Serial in. 618,178.

M inventionrelates to improvements in 11111810211 instruments of ,the type wherein a ment, commonly referred to as an electric carillon, which faithfully reproduces the sounds of chimes and bells. In this connection, it has been found that the capability of the instrument to exactly reproduce the sound of 'a chime or bell depends on a number of structural and physical characteristics of the vibratory element. The various constructions of vibratory elements proposed heretofore have been capable of reproducing the sounds of chimesand bells with some degree of fidelit but therehas always been a very noticeable distortion of some kind.

For example, the vibratory elements roposed heretofore have been too rich in ar- 55 monies to be of any use in exactly reproducing the soundsof bells and chimes, and,

furthermore, these elements have lacked the characteristic harmonics of bells.

, With the foregoing in mind, it is one of the objects of my invention to provide an v imgiroved vibratory element of the character re erred to which is capable .of falthfully replroducing a musical note .of a chlme or #5 Other objects and advantages will herein after appear. 7

For the urpose of illustratin my invention, an em odiment thereof is s own in the drawing, wherein Figure 1 is a front elevational view of a p rtion of a musical instrument constructed and set u in accordance with m invention;

Fig. 2 is an end elevational view, looking toward the left of the device shown in Fig.

1; and

Fig.3 is a table of dimensions for a vibratory element constructed in accordance with my invention, and capable of faithfully reproducing. the notes of chimes or bells range ofone octave.

In Figs. 1 and 2, the vibratory element 10 is capable of reproducing a musical note having a definite pitch frequency, and may be considered as being one of a number of such elements. mounted in bank formation and constructed and adjusted to reproduce the respective notes in the musical scale. One manner of supporting .and operating thevarious elements is disclosed in the cop'ending application of Carroll ,D. Kentner, Serial N 0. 574,961, filed November 14, 1931 and assigned to the Radio Corporation of America.

As shown, the end of the straight por--.

tion of the element 10 is clamped between suitable blocks 12 and 14 by screws 16which pass loosely through the block 14 and thread into the block 12. 1 For the purpose of transforming the physical vibrations of the element 10 into electrical pulsations, the element is supported with its straight portion extending through an air gapin a magnetic circuit which'may be provided by'a permanent ma net of suitable form (not shown). A pic -up coil 18 is 'so disposed in the magnetic circuit that, as the element 10 vibrates in the air gap, a current is. induced in this coil at a frequency corresponding to the frequency of vibration. This current is then amplified and supplied to a louds eaker or other acoustic device (not showng.

- A striker, which may be in the form of a hammer 20, is suitably supported for manual or electrical operation to strike the element 10 and to set it into vibration.

Coming now to the essence of my invention, this resides in the construction and adjustment of the vibratory element or elements such that any particular element for reproducing a musical note of a definite pitch frequency has characteristic relations between certain structural dimensions of this element and the pitch frequency.

@ne of these dimensions'I refer .to as the total vibrating length L of the element, and measure this from the edge of the clamping blocks 12 and 14 to the free vibrating end-22 of the element. In my improved construction, L=Aw, wherein a: is

is an exponent of 2; within the range of .48 to .495. Very satisfactory results have been obtained by making A substantially equal to 598.3, and by making a substantially equal to .487.

Another important structural dimension in my improved construction is the hanging length HL, which is measured, as shown in Fig. 1, from the edge of the clamping blocks 12 and 14 to a line tangent to the spiral portion 24 of the vibratory element, and perpendicular to the straight portion of the latter. In my improved construction, HL=Ba wherein HL. is the hanging length of the vibratory element in inches, B is a factor within the range of 70 to 75, and b is an exponent of :1; within the range of .335 to -.380. Very satisfactory results have been obtained by making B substantially equal to 72.4, and by making 6 substantially equal to .36.

Another important dimension in my improved construction is the outside diameter D of the spiral portion 24, the relation being D'= Cm", wherein D is the outside diameter in inches, G. is a factor within the range of to 75, and c is an exponent of w within the range of .365 to .45. Satisfactory results have been obtained by making C substantially equal to 70.4, and by making a substantially equal to .41.

Another important structural character- 'istic of my improved vibratory element is the number of degrees through which the spiral portion 24 extends.

In the particular embodiment ,of my invention disclosed, the spiral portion 24 extends through one complete revolution from E to F in a counter-clockwise directionfand then continues on further through about 230 degrees. In vibratory elements constructed in accordance with my invention, the number of degrees through which the spiral extends is within the range of from 500 to 620 degrees. extends beyond this range, the tone reproduced is too rich in harmonics, and that if the spiral does not come within this range the vibratory element lacks the characteristic harmonics of a bell of the corresponding note.

I propose to make the elements 10 from a very high grade tempered steel, the steel being tempered to between 1400 and 1500 degrees Fahrenheit, the material being gauge. Any other material, or combination of materials, having the required characteristics, may be used to make the elements 10. The width W of the material is to be from to The width of the element does not affect the tone color, and

I have found that if the spiral is selected only to provide the desired stiffness.

For the pn ose of preventing rusting of the elements}? propose to give the same a very light coat of cadmium. This is done without any run of temperature, or other conditions which might change the tonal qualities of the instrument. As is shown in Fig. 2, the tongue of each element, or that part which goes between the clamping blocks, is slightly tapered, the tapered length being approximately of the total length of the reed measured from the point of support. The width w of the reed at its clamped end is-about A of the width W. The reason for this shape is to prolong the sound from the reeds, or to reduce the attenuation of the sounds or vibrations as might be desired.

Any particular element is tuned exactly to the desired note by loosening the screws 16 and varying the hanging length HL, which also increases or decreases the total vibrating length of the reed, to the proper point.

The various dimensions given in Fig. 3

have been found to be satisfactory for a I set of vibratory elements covering the various notes in the musical scale from the C one octave above middle C to high G.

I claim as my invention:

1. A vibratory element of the coiledspring type for producing a musical note having a definite pitch frequency, characterized by the existence of the following relations between the structural dimensions of said element and the pitch frequency: L=Aw; HL=Bw"; and D=Cw; wherein m is the pitch frenquency, L is the total vibrating length of said element in inches, A is a factor within the range of 595to 605, a; is an exponent of :1: within the range of .48 to .495, HL is the hangin length of said element in inches, B is a actor within the range of 70 to 7 5, b is an exponent of a: within the range of .335 to .380, D is the outside diameter of the coiled portion of said element in inches, C is a factor within the range of 65 to 75, and c is an exponent .of as within the range of +365 to .45.

2. A vibratory element as claimed by claim 1, further characterized by the fact that the coiled portion of said element is in the form of a spiral wherein the number of degrees through which the spiral extends is within the range of from 500 to 620 degrees.

3. A vibratory element of the coiledspring type, for producing a musical note having a definite pitch'frequ'ency, characterized by the existence of substantially the following relations between the structural dimensions of said element and the pitch frequency: L 598.3% .487; HL=7 2.411% .36; and D=70w-.41; where a: is the pitch frequency, L is the total vibrating length of said element in inches, HL is the ban g length of said element inches, and is the outside diameter of the coiled portion of said element in inches.

4.- A vibratory element as claimed by claim 3, further characterized by the fact that the coiled portion of said element is in the form of a spiral extending through substantially 590 degrees.

In testimony whereof, I have hereunto subscribed my name this second day of June, 1932. ARTHUR N. CURTISS. 

